The Thirteen is a supporting booklet for Hudson & Brand, Inquiry Agents of the Obscure for 7th edition Call of Cthulhu, and is an official Cthulhu by Gaslight product. This chapbook introduces an organisation of immortals, for the benefit of Keepers who wish to add something a little unusual to their games.
While there are no chapters, the 15 different sections of the book can be grouped together, roughly, as follows:
Section 1: The Society of the Thirteen. These sections introduce a new organisation of Mythos-aware NPCs, set in foggy Victorian London. The book starts off by covering their history, complete with a timeline dating back to the late Stone Age, from when (and how) they first gained immortality, up to the Victorian era.
Sections 2-5: Summary of the Society of Thirteen: The Society of Thirteen are, basically, human, and can serve easily in the role of enemy, ally, or merely other interesting NPCs for your investigators. These sections details some of the role-playing challenges a Keeper should expect when playing ancient humans, and a couple of driving motivations for the members of this group. Also covered is how members of the society keep the Sanity-rending effects of the Mythos at bay, and how they cope with all they’ve seen over the millenia.
Section 6: Playing the Society as an Organisation: This part covers the organisations group motivations and goals, what their limitations are, why they stay together, etc. It also delves into how they typically interact with outsiders (like those nosey Investigators). Lastly, it covers the resources that the Society of Thirteen has, including The Whiteacre Estate, some 10 miles to the west of London (easily reached from 33 Golden Square), as well as the source of their power/”immortality.”
Sections 7-14: The Society Members: These portions of the chapbook covers the surviving members of the group (and provides a list of the deceased members and what role they had served while still living). Each NPC is provided with a detailed history, their role in both the Society as well as Victorian-society, a stat block, encounters with famous, past figures they may’ve had, and then tips on role-playing each member.
Sections 15-16: Dealing with External Threats: The final two sections cover how the organisation will react to the deaths of any members as well as how they may react, long-term with any investigators that have been useful to them.